In an image taken by a digital camera or the like, resolution on a periphery of the image has often been reduced. The resolution on the periphery of the image tends to be reduced as compared to the resolution in the optical axis central part due to aberration of a lens optical system and the dependence of an aperture size on an angle of view. One of the causes of this reduction is aperture vignetting. In a portion with a wide angle of view, vignetting occurs in an aperture in a radial direction and causes the aperture to be elliptic, which causes blurring. This reduces the resolution in a radial direction.
To deal with such a reduction in resolution, there is, for example, a technique of performing image correction by performing filtering by using different filter data in accordance with a position to be processed in an image to meet changes in a point spread function (PSF) caused by the angle of incident light (see, for example, Japanese Laid-open Patent Publication No. 2012-23498).